Lift post especially for lift trucks



Feb. 23, 1960 H. A. KAGEL LIFT PosT ESPECIALLY FOR LIFT TRUCKS 4 Sheets-Sheet l Filed March 21. 1957 wf/vra@ /QLW Feb. 23, 1960 H. A. KAGEL LIFT POST ESPECIALLY FOR LIFT TRUCKS 4 Sheets-Sheet 2 Filed March 2l, 1957 Feb. 23, 1960 H. A. KAGEL LIFT POST ESPECIALLY FOR LIFT TRUCKS Filed March 21. 1957 4 Sheets-Sheet 3 .v1 A ,111| iii /NVEN'OP Feb. 23, 1960 H. A. KAGEL LIFT POST ESPECIALLY FOR LIFT TRUCKS Filed March 21. 1957 4 Sheets-Sheet 4 ws/vra@v cation in connection with the accompanying LIFT POST ESPECIALLY FOR LIFT TRUCKS Hans A. Kagel, Bergisch Gladbach, Germany, assigner to Vereinigte Westdeutsche Waggonfabriken Aktiengesellschaft, Koln-Deutz, Germany Application March 21, 1957, Serial No. 647,513 Claims priority, application Germany March 28, 1956 11 Claims. (Cl. IS7- 9) A1 The present invention relates to a hydraulically, actuated lift post for transporting and loading devices, -especially lift trucks. In most instances, such lift posts consist of a stationary'and a movable post member which latter has guided thereon a slide for receiving and supporting the load. With lift trucks, the lift post is arranged at the front side of the vehicle, while the slide with the supporting fork for the load is arranged on the front side of the post. The stationary and the movable lift post portions are subjected to bending by the load, whereas the lifting cylinder carries the load only.

It is, therefore,an object of the present invention to provide an arrangement which will overcomethe above mentioned drawbacks.

It is a further object of this invention to combine the lifting cylinder with ,the lifting post in such a manner that the total-number of structural elements will be reduced thereby making it possible to reduce the total lift post, particudrivers view from the drivers seat will be considerably improved.

These and other objects and advantages of the invention will appear more clearly from the following specidrawings, in which: Fig. l represents a view of a lift truck equipped with a lift post according to the invention, the latter being shown in longitudinal central section.

Fig. 2 is a horizontal section through the lift post taken along the line -II---II of Fig. 1.

Fig. 3 shows in perspective the upper connection of a piston rod with the movable post member for actuating the same.

Fig. 4 diagrammatically illustrates the possibility of braking the working piston at the end of the downward stroke.

Figs 5, 6 and 7 show the connection of the load chain with the stationary post member.

Figs. 8 and 8a diagrammatically illustrate the condi- `tions of the free lift for a lift truck equipped with a lift nal vertical plane of the lift truck.

i G eneral arrangement The arrangement according to the present invention is characterized primarily in that the lifting cylinder is so designed as simultaneously to serve as lift post. The

.combination of the lift cylinder with the liftJpost or the 2,925,838 Fatented Feb. 23, i960 construction of the cylinder itself as bend-resistant beam or post considerably reduces the number of structural elements, the weight of the post, the dimensions of the post and the View of the driver ofthe vehicle.

The design of the lifting cylinder as lift post will, of course, make it necessary that the outside'of the cylinder will have a profile which will make it possible to take up the occurring torsion forces. According to a most simple construction, the outside ofthe lifting cylinder is so designed that its cross section Will be rectangular or square.

In conformity with a further development of the invention, the movable post member surrounds the profiled cylinder preferably on all sides. A closed hollow cross section has the advantage, as is well known, of a maximum resistance against torsion.

For a particularly satisfactory guidance of the slide it is advantageous to provide the outer post member with recesses extending on both sides of the slide and on the outside thereof along the same. Preferably these recesses are arranged at a rectangle with regard to the longitudinal direction of the vehicle. The free flanges which convey the guiding forces simultaneously act as reinforcing marginal portions of the beam or post. This has a favorable effect as to the saving of Weight.

The longitudinal recesses of the movable post member are engaged by rollers with pivots facing each other, said rollers preferably being journalled in said slide. These rollers may also be provided with conical surfaces and accordingly may be guided by inclined counter surfaces of the recesses of the post so that the same rollers will simultaneously convey forces directed in the direction of their axes.

Structural arrangement Refeiring now to the drawing in detail, the lift post shown therein consists primarily of the stationary post member 1 and the movable post member 2. Slidably guided on the movable post member 2 is a slide 3 carrying a supporting fork 4. The stationary post member 1 is in conformity with the present invention designed as working cylinder and has reciprocably mounted therein a piston 5. On the upper end of the piston rod 6 is journalled a sprocket 7 over which passes a chain 3. This chain is preferably but not necessarily a so-called ilyer chain having one end thereof connected to the upper end of the stationary or fixed post member 1 while its other end is connected to the slide 3. The piston rod 6 is ixedly connected to the upper end of themovable post member 2'. It will thus be evident that the slide 3 carries out a stroke which. is twice as long as that of the piston and of the movable post member.

The fixed post member 1 serving simultaneously as working cylinder has its outside shaped so that the outer cross sectional contour of the fixed member 1 is square shaped. The iixed post member 1 is preferably produced by Welding together or hard soldering of two drawn profiles along gaps 10 which for instance may be ,located in the p lane of the neutralzone at which the sorbed. The outer surfaces preferably form the guiding .surfaces for the movable post member 2 which telescopically engages the outer surfaces of the stationary post ,.member., In order to improve the sliding conditions, metal plates or bearing members 11 are arranged between the two post members.

For manufacturing purposes, these metal plates or layers 11 are preferably arranged on the outer surface of the stationary post `member 1.4 .These metal plates or layers may in view of the elastic exure of the post be unevenly thick .so that the aXial forces which subject the piston rod to buckling stresses will not move out too far from the theoretical axis. It is, of coursegunderstoodthat the'lifting cylinder may be designed simultaneusly ias post ilso 1in various other manners. Thus, for instance, a tubular .cyiinder could be used and could have Aits outside reinforced l,so as simultaneously to Aform.guidingsurfaces -for the Vmovable post member. -A

The lower end of'th'e stationary 'or ix'ed postmember 1 is by means of screws 37 connected to the transmission casing 9 which latter forms a -part rof the vehicle body 33. The bottom-portion ofthe cylinder 1;is closedfby a detachable lid 12 so that the piston 5 will be accessible from below whenever necessary and can -be assembled from below.

The'movable 4post member e2 forms over the major zportion of its length a body 4which is lclosed, on 'all sides. .The movable post member 2 may :be produced from two rolledand drawniproles orstructural members offabout double-T shapedcross section,the 'neutral Zonessubstantially .coinciding with the vertical transverse plane yA-B `(Fig. 2). The two proles `or structural members maybe connected `directly to veach other. However, according to the particular construction shown in the drawing :two intermediate members 512, 13 `of less cross section -are respectively arranged fat lthe :rear and vat the :front :of the post Vso that the lchain 8 will be arranged iat ithe rear within and lat the front voutside the Vmovable post member. Theintermediatemernbers 12, 13 rare `primarily due to considerations in-connection with thegproduc .tion fof the double-T structural members designed Vas ,rolled steel members. 'The lateral protruding A,portions 15 of .thezmovable post vmember 2 lform vtheginnercon- .tacu'ngsurface 16 forth'e guiding-rollers -17 of the slide 3. inclined surfaces 1S are furthermore provided-tor absorbing the axialforcesof ltherrollers17. The double-T protiles or structualm'ernbers combine the properties of 'an inn'erand outer guide with lhighly resistant'torques `against bendingland `with polar inertia moment against torsion.

As has been clearlyindicated in Fig. l, the movable post member VvZhas its back sideslit over a certain distance'fsothatthe lower end ofthe post member 2 can movelabove that range of the Xed post member 1 over which the latter is connectedto` the vcasing 9. The xed or stationary post member l'has its upper end provided Vwithfa'slit 38 '(see Fig. '51) which makes:it:poss'iblertliat the movable vpost member 2 'can be 'moved downwardly completely 'over'thejstationary'fpart1in which instance lthe lprotruding portions of'thehcad of the piston rod 6 will enter the'slit 38. H

The cross section through thepost as shownin'FigfZ yclearly shows the eccentric journalling of the sprocket 17 on the pivot 20. The ecce'ntricity -of the axis of said verse web'21. Thefrontand rear Yendsfof ythezwebf-Zl fengagea correspondingfrecess yof Athe -rriovable-'post-12. The web 21'is connected to'vth'e piston rodfofasiwe'llas tothe movable post Z'Jfor' instance by welding. The chain Asprocket 7: sharply 'protrud'es through the'do'wnwardly-extending slitofthe'p'ost 2 so vvthat 'the chain-nieves-l infa :grooveoutside thev post as isy clearly evident*frc'n'nFig;y 2.

With-regardtoFig.3,*itmay bei added that thisgii're .showsfcorner pieces 59'v welded to two upper' cornersvof theY movable-posti The purpose 'of' thesevcornerI members 591consists. in reinforcing the1upperffreeends ofthe guiding path for the rollers` 17. The front'ledges 15 against 'sprocketcorresponds'to the guiding of the front portion v `ofthe chain outside the'mov'able post 2 and-also corre- `sponds'to theguidingof the rear 'portion of thechain inintermediate portion oftheirlengths subjected to `considerably less stress than their upper free ends. Therefore, the said upper free ends of the front ledges 15 have been reinforced bythe corner pieces 59. Of course, if the ledges 15 are correspondingly stronger dimensioned, a reinforcernent by corner pieces such as the'corner pieces 59 will'not be necessary.

Fig. 4 diagrammatically illustrates the piston 5 in the lower portion of the stationary 'post v1,. As will lbe seen from Fig. 4 in particular, the'lower end fof -the piston has a unilaterally inclined Vvsurface 22 which 4during the last portion of the downward stroke of the piston gradually closes oil1 the passage 23 for the admission and discharge of oil under pressure. Itasuddenrelief ofthe oil pressure conduit occurs, the last portion -of `the piston stroke and of the movable post is braked Vover a certain distance so that shocks and overloads will be avoided.

Fig. `5 v illustrates the connection of the chain S'Wth-Lthe stationary post 1 through-the intervention 'of ia chain 'closure member 24 connected to post 1 by means 'of'screws 35. The chain closure member Which'is shown on 'an enlarged scale in Figs. 6 and 7 has a transverse bore -25 'and a -longitudinal bore -26 'for discharging leakage oil 4fro'rnithe working cylinder whichma-y `escape along the pistons'eal 36 (Fig. 4). By combining'therleakage discharge withthefchain'closurememben the corresponding structural elements can be designed shorter.

Figs. `8 and 8a -diagrammatically zillustrate ith'e :longitudinal dimensions `or rations for the `:above `mentioned rstructure of ya 'fixed connection between the piston 'fro'd and the movable post. The term freestroke 'asit will `presently be usedfdesignates :the stroke"fs'from the 'en- 'tirely 'downwardly moved condition of the Sforlcs y4 :,up'to the level vto vwhich they z-move'lun'til ythe'rnovablepost does not'yet fprotrude above vthe rixedipost. vIn `other'words ir'eefstroke"v designatestwiceethestrokefrom theentirely downwardly moved position of t-lremovablefpostfup yto "is Vloc'ate'dat thelevel of thevuppenend ofthemovable xpost. 1Inits'entire'1y downwardly moved position, thev movable'post' protrudes somewhat downwardly' under' the lower :endof vthe movable post. Atfthefend-of the .free:stroke, V.the upper ends of both posts are atfthe same level. If vthem'ovable post is lifted furthen'aportio-n:ofthe movable post and of the piston rod protrude abovethe 'head ofthe lifting cylinder. vIf, whendriving through'low un- Aderp-asses; the 'post is slightly toohighfonlytheglesssensitive? rnovablefpvosty receives 'afshock whereasithe piston' rod is protected.

`Duextothe Vfact that the piston :ro'd never protrudes "above the ,movable post it 'ismade possible l; advantageously to cover up the'interior :of vthemovable post bya plate 33 shown in Fig.f9"thereby preventing. dirt and other foreign particles from entering' into-'thc interior of the yrnovabie post. The plate -0=isresiliently supported so vas tofbe '-yieldable Aby `a stroke equaling'half the Afree stroke, so that the movement of the movablepost will v'not --be' impeded-when' the-slide' '3 is inl its lcwermost position. lDue-to the-small widthofzthe-ypostl according Vto the present invention, the driver of the vehicle has #a parmore adapted to dr'iyeani additional *oil* pressure'fpump Q41 fiar-:ase uiting rangen-lavementreferencian.

epesses Ihe oil pressure pump 40 through conduits 42 and 43 feeds. two hydrostatic. driving motors 44 for the twofront wheels 45. The rear wheels 46 are not positively driven but are merely steered in a manner not shown in'the .drawing inasmuch as this steering mechanismdoesnot form a part of the present invention. `Through the interlvention of a valve 48 adapted to be actuated by a lever 4 7, ,the oil pressure pumpv411feeds oil into the lift cylinder for the fork` 4. This is effected through a conduit 49, and a passage 23 in the stationary post 1. Due to thedirect connection of the post 1 with the transmission casing 9l and due to the direct passage of the pressure oil from the transmission casing 9 into the post 1, a high pressure conduit is'avoided which would have to be arranged On-th outside of vehicle body and would be sub-jectgto damage. AAll pressure oil conduits lfor the driving liftingand Vtilting operation" are .located within the. transmission casing 9 and-are thus protected against damaging influences from the outside. n

Leakage, oil which escapes due to certain leakages of the various conduits,v is collected in the transmission casing 9. inasmuch as the transmission casing 9 simultaneously may be used as oil sump for the pump 41, and if desired also for the pump 40, any loss of oil'will be avoided. ,V rI `he. axle 50 of therear wheelsr46 is tiltable about a pivot axle 52 by means of l,tiltablelevers 51 extending lin longitudinal direction of the vehicle body 33. The rearends o f the twolevers 51 are provided with a ceunterweight v53. Whenintroducing pressure oil from the pressure pump 41 into the tilting cylinder 55 through the control valve 48 and. they conduit 54, the entire vehicle body 33 and thus .the posts 1, 2 together with the fork 4 is tilted about the axle 5 6 vof ,the front wheels 45. During such a tilting movement, vthe inclination of the fork 4 changes as is necessary for loading and unloading the fork. The dischargehof leakage oil which may pass bythe piston, 5 Vin the upper portion ofl this post 1vflows back into the transmission casing 94 through the ychain closure member 24 connected to post 1 and through the intervention of a conduit 57. v.

lIt is, of course, to be understood that the present invention is, by no means, limited to the particular construction shown in the drawings but also comprises any modifications within the scope of the appended claims.

What I claim is:

1. A hydraulically operable lift post system for transport and loading devices, especially lift trucks, which includes: a stationary post member, a movable post member telescopically engaging the outside of said -stationary post member, said stationary post member forming a cylinder provided with passage means for receiving actuating fluid and 'discharging the same, said movable post member having two sides thereof provided with tracks having plane main guiding surfaces substantially parallel to the longitudinal axis of said post and having auxiliary surfaces also extending substantially parallelto the longitudinal axis of said post but respectively forming an obtuse angle with the adjacent main guidingsurface pertaining to the same track, avslide, roller means respec'- tively supporting said slide and provided with cylindrical peripheral surfaces and with conical end faces for engaging said tracks along said main and said auxiliary guiding surfaces respectively whereby said roller means will absorb radial as well as axial forces, said slide being arranged for supporting a load-receiving and supporting means, and piston means reciprocably mounted in said cylinder and connected to said movable post member for actuating the same.

2. A hydraulically operable lift post for transport and loading devices, especially lift trucks, which includes: a movable post member and a stationary post member telescopically arranged with regard to each other, said movable post member being composed of two structural members of substantially I-beam cross section arranged in spaced relationship to each other, a first connecting member having a thickness less than the thickness of said structural'members and connecting the same so as to have its outer surface set back with regard to the adjacent outer surfaces of said structural members thereby confining therewith a groove open toward the outside, a second connecting member having a thickness less than the thickness of said structural members and connecting the same so as to have its inner surface set back with regard to the adjacent inner surfaces of said structural members thereby confining therewith a groove open toward the inside, said stationary post member forming a cylinder provided lwith passage means .for receiving actuating fluid and discharging the same, plunger means Ireciprocably mounted in said cylinder and connected to said movable post member for actuating the same,` a sprocket wheel supported by4 said plunger` means, and a chain passing over said'sprtocket wheelA and having one .end fixedly connected'to said stationary' post member and having its-other end arranged for supporting a slide, one branch of said chain carrying the end for connection with a slide passing through the groove open toward the outside of said post, while the otherbranch of said chain passes inside of said second connectingmember.

3. A hydraulicallyoperable lift post for transport and loading devices, especially lift trucks, which includes: a movable post member and a stationarypost `member telescopically arranged with regard to each other, said movable post member being composed of two structural members o f substantially I-beam cross section arranged in spaced relationship to each other, a first connecting member .having a thickness less than the thickness of said structural members and connecting the same so as to have its outer surface set back with regard tothe adja'- cent outer surfaces of -said structural members thereby'r confining therewith a groove open toward the outside, asecond connecting member having a thickness les's than fthe thickness of said structural members and connecting ,the same so as to have its inner -surface setback with regard to the adjacent inner surfaces of said structural members thereby confining therewith a groove open toward the inside, said stationary post member forming a cylinder provided with passage means for receiving actuating fluid and discharging the` same, plunger means reciprocably mounted in-said cylinder and connected to said movable post member` for actuating the same, the upper end portion of said plunger means being provided and having its other end arranged for supporting a slide, one branch of said chain carrying the end forconnection with a slide passing through thegroove open 4toward the outside of said post, while the other branch of said chain vpasses inside of said second connecting member.

4.2 A hydraulically operable lift post for transport and yloading devices, especially lift trucks, which includes: a movable post member and a stationary post member telescopically arranged with regard to each other, said movable post member being composed of two'structural v member'sof substantially l-beam cross section 1arranged in spacedrelationship to each other, a first connecting memberhalving -a thickness less than the thickness of said structural members and connecting the same so as to .have fits outer surface set back with regard to the adjacent outer surfaces of said structural members thereby confining therewith a groove open toward the outside, a second connecting member having a thickness less than the thickness of said structural members and con necting the same so as to have its inner surface set back with regard to the adjacent inner surfaces of said structural members thereby confining therewith a groove open toward the inside, said stationary post member forming a cylinder provided with passage means for receiving actuating fluid and discharging the same, plungirnember.

*7. An arrangement saccording v,to -claim 6,-A inriwhich*v 7 er .means recproobly mounted in Said .Cylinder :and connected 'to said A rrrovable post vrnernber for actuating the same, the upper enti of :Said Plunsorvmearls boing provided With ltwo upwardly, extending ,prong-Shaped portions Jeavingarecess ftherebetween, a -sprocket Wheel rotatably Vsupportedjhy'gsaidplunger 7,means and arranged between said prong-shapedportions, and a chain passing over .said .sproket wheel .and hav'ing one end-*rtxcly connected to said Asta1tionary,postmember an'dhaving lits other end arranged jfor supporting Va slide, said prongshaped pportions extendingupwardlybeyond said sprocket Wheel to c oniine with Vthe Aperiphery :of said `sprocket wheel a passage j'for :said 'chain, one `branch of -sai'd chain carrying the end or connection Awith a slide'pass ing lthrough pt lreggrqove open"toward thjeoutside 'of said jpost, while the-other nchnof jsaidchainpasses inside off-,said second connecting member.

5. A lhydraulically g(mer-able jlift 'post structure rfor `transport and jfeloadingfdevices, 'especially lift trucks, which includes: ja movable=post member and a stationary post member `Atelescopicall'y arranged with regard to each other, said stationary post member'forminga cylinder provided with passage ineausfor receivingactuating "fluid and discharging 'the Asamejplungermeans 'reciprocablymounte'din said cylinder 'and extending upwardly substantially toi-,the upper end Aof said 'movablepost-member, the upper. vend portion ofsaid jplungerymeans being Provided withtWo-upwardly:extending prongs so as to 'form ;a cutout therebetween, ajtransve'rse member -extending into VVSaid ,cutout between fsaid prongs and corinectcd tok f said plunger vmeans gand `the -'upper end of saidmovabledpost member, and l'a1-sprocket wheel Vrotatably .Supported "by fsaidgprongsiaud .fi-arranged 'within said cutout.

6. A hydraulically operable 'lilift post structure fior vtransport and loading devices, `especially lift ftrucks, which includes: ,,aggnovablejrpost'member @anda y*stationary ,'PQStmenibctelescopicaily ,arrangedv with' regard-'to cach other, said stationaryjjpostmernberforming a cylinder lprovided with passage lmeans for .receiving actuating lHuid and dischargingthe sameLplungeLmeans reciprocably mounted in said cylinder andhaving its upper end connected to said ymovablebpost member "for ,actu-ating the same, the upper-end of said plunger meanbeing provided with:a cutout, a sprocket wheelrrotatablysupvported by said zplunger VYlrnearmlsjanfd arranged-within-said cutout, 'a ',Slde f arranged v"for supporting load-receiving fand supporting .means eudjsoided rfloris ,Said movahlo :post member; :and to :Chain ,Passing "over i-Saiid fsprookot 4v vheel ardfihaving 'one 'end thereof vconnected Ato `said slide vvand having its j other end fcounecteil to Ysaid f startionary lpost member, fthe axis of rotation Iofjsai'd "sprocket"'wheel1 being ofset 'fwitnregard f to --vthe vcentral longitudinal axis-vof said'cylinder4 so'ithat lthe `chainsportion connectedtosaidgjslide'will -always movev substanstially; along'fa path'parallelitothc pathsofthe-other chain portion-'extending lfrorrvsaidfsprocket'wheel'to the con- :necting jpoint vof vk'said "chain 'withssaid `stationaryjpost *that'send v'portion `ofj ther-chain vfv hi` -is 1 connectedl tothe -,stationari/post mentber'@reprises ondutgmolansrharios Vonesendeconnectedito theintc'rior fof fthcupper cylinder ademas portion lfor receiving -rleakage foil and Vhaving :its other e'nd 'connected rwith a discharge for the teeeived-*lealcage oil.

y'8. Aghydrauliea'lly operable liftpoststructureffor--transport andfloading devices, especially 4'lift j-trucks, -Which includes: arr/inner stationaryshollowjpost memberforming a ,eylinder-with passage means for receiving actuatinfgluid Aand diseharginggtthe same, said inner Vpost mem- -brbeing `composed ofr'structuralmembers with profiled outer surfaces, an out-,er hollow post member telescopilcaliyfslidabiy mounted on said innerpost member, lsaid router l*post rnember being composed lof structural `mern- `-bers having :the Ainside thereof proled in comformity with Lthe contour 4vof `|said profiled vouter surfaces of said 'innerjpostgmembegso 'ase'to be guided vand secured thereby against rotation, the v-outer surfaces of said strucltur-al fmembers f Rsaid =outer-post member having :a contour .fdening Vguiding track --ifn eans, fluid operable pistou V means reciprooably mounted in said cylinder and connectedf-tof'saidJouterjpostmemben-thesupper end of said -vouter post 'e member 'being provided -with a cutout, a sprocketwheel rotatablymountcdin said cutout, a`load -carryingsslidq ya*chain-passing lover said sprocket wheel andihaving'oneend-conneotedftosaid inner post member and` having'its other -end 'connected to said slide, and guidingroller-lmeaus mounted onsaid sli'deand engaged 'by s,ai`dyt1jack meansso assto-be guided thereby. F

519. ffhydraulically operable lift fp ost structure `accordplane substantially perpendicular-sto the neutral Zone Vof'.the"bending stresses exerted upon said outer hollow post member,

ll. A -=hydraulicaily operable lift post structure for useirl-connection'withfaliftutruck having a chassis and which-said"innerstationaryhollow post member has a e lower wall portion of increased thicknessfor connection with-ther-chassisjofsaid,lift truck, said wallzportion'being provided withg-a;passagefegrtending through said Wall poi'- -tionsf'or #connection yiyithf said pressure f'luidv supply" sys- 1 temofsaidtruck.

References @iisd in the-file-,ofthis patent f1-uNrrED1sTA'res :PATENTS 

